Membrane electrode assembly electrolysis system fed with pure water and method for manufacturing the same

Abstract

The present application presents a pure water fed membrane electrode assembly (MEA) electrolysis system for electrocatalytic CO2 reduction (ECO2R) to produce C2H4 and C 2+ compounds, and have a lifetime of at least 1000 hours.

Description

Technical Field

[0001] This invention relates to an electrolysis system for pure water feed in electrocatalytic CO2 reduction (ECO2R). Specifically, this invention provides a membrane electrode assembly (MEA) electrolysis system with pure water feed, which is applicable in industrially viable ECO2R production of C2H4 / C. 2+ The compound is used under continuous flow conditions with a high-performance, step-rich copper (SF-Cu) catalyst, thereby achieving a lifespan of over 1000 hours. Background Technology

[0002] ECO2R has a wide range of applications, such as using renewable electricity to produce high-value chemicals and feedstocks. This can decouple chemical and fuel production from fossil fuels, thereby closing the carbon cycle and offering the possibility of reducing greenhouse gas emissions. Optimizing the selectivity of high-value-added products (i.e., Faraday efficiency (FE)) such as carbon monoxide, formic acid, and ethylene; increasing their productivity (current density); and reducing the overpotential of these reduction reactions have become priorities, and some significant progress has been made. However, the stability of the electrolysis system remains a serious problem. The formation and exchange of carbonates in alkaline or neutral electrolytes during electrolysis leads to additional energy consumption and CO2 loss, thereby reducing the durability of ECO2R.

[0003] Another problem is that the strong local alkalinity in the ECO2R causes most of the input CO2 to react with hydroxide ions (OH-). - The reaction produces carbonate (CO3) ions. 2- Instead of being reduced to carbon-based products, CO2 is converted from carbonate, thus reducing reduction efficiency. Some recent studies have shown that regenerating CO2 from carbonate in a calcination system requires more than 230 kJ / mol of energy; however, depending on the products, ECO2R stores only 100-130 kJ / mol of electronic energy, indicating a negative net energy balance in alkaline / neutral electrolytes.

[0004] In principle, since each electron in ECO2R can consume one hydroxide ion equivalent, taking the production of ethylene (C2H4) in an alkaline / neutral electrolyte using ECO2R as an example, the formation of one C2H4 molecule will generate 12 hydroxide ions. These hydroxide ions can react with 6 CO2 molecules to generate 6 carbonate ions (reaction formulas (1) and (2)):

[0005] Cathode: 2CO2 + 8H2O + 12e - →C2H4+12OH - (1)

[0006]

[0007] Therefore, the theoretical maximum carbon efficiency of ECO2R for producing C2H4 is 25%, and in actual electrolysis, due to the low efficiency of the cathode catalyst and the use of a strongly alkaline electrolyte, this theoretical maximum carbon efficiency is even far lower than this theoretical limit. Furthermore, the large amount of carbonate formed precipitates in the gas diffusion electrode (GDE) and CO2 flow channels of the electrolyzer, thereby hindering CO2 mass transfer, accelerating electrolyte overflow, and ultimately causing the ECO2R reaction to shut down. These factors contribute to the extremely poor stability of ECO2R. To date, the stability of ECO2R for producing C2H4 in alkaline / neutral mobile phase electrolyzers or membrane electrode assemblies (MEA) electrolyzers is typically less than 200 hours.

[0008] In anion transport electrolyzers equipped with anion exchange membranes (AEMs), carbonate ions formed at the cathode are transported to the anode, where they are protonated and release CO2 and hydroxide ions. This process can consume up to 70% of the input energy. Although acidic (pH < 1) mobile phase electrolyzers improve CO2 utilization by eliminating carbonate formation and permeation at the cost of some ECO2R products, such acidic electrolysis systems do not meet the requirements of industrially promising MEA electrolyzer architectures, such as... Figure 1A and 1B As shown. Therefore, there is a need for an improved MEA electrolyzer system that can eliminate or at least reduce the aforementioned drawbacks and problems. Summary of the Invention

[0009] Therefore, this disclosure provides a pure water-feed MEA electrolysis system on a high-performance, step-rich copper (SF-Cu) catalyst, which exhibits rapid reaction kinetics for the ECO2R to C2H4 production. The system integrates an AEM and a proton exchange membrane (PEM) to selectively transport the generated hydroxide and hydrogen ions (H+) respectively. + This system not only enhances the ECO2R reactivity of pure water feed by increasing the local pH on the cathode catalyst surface, but also eliminates carbonate formation and permeation, thereby extending stability.

[0010] This invention provides a membrane electrode assembly electrolysis system with pure water feed, which is used for the electrocatalytic reduction of CO2 to C2H4 and C under industrially applicable continuous flow conditions. 2+ Compound, C 2+ The compounds include ethanol, propanol, and acetic acid. The membrane electrode assembly electrolysis system has a lifespan of at least 1000 hours, wherein the system comprises one or more membrane electrode assemblies, and each membrane electrode assembly includes:

[0011] anode;

[0012] cathode;

[0013] Anion exchange membrane;

[0014] Proton exchange membrane;

[0015] A copper catalyst with a stepped surface at the cathode; and

[0016] Electrolyte

[0017] in:

[0018] The cathode is arranged to contact the anion exchange membrane;

[0019] The anode is arranged to contact the proton exchange membrane;

[0020] Anion exchange membranes and proton exchange membranes are arranged to be in contact with each other;

[0021] The electrolyte is selected from pure water. In the forward bias mode of the system, pure water is used as a proton source for electrocatalytic CO2 reduction at the cathode.

[0022] The anion exchange membrane is selected from basic anion exchange membranes or bipolar membranes; and

[0023] The proton exchange membrane is selected from acidic proton exchange membranes or bipolar membranes.

[0024] In some embodiments, the cathode is selected from a gas diffusion electrode having at least one layer of copper catalyst rich in step surfaces deposited on it.

[0025] Preferably, the cathode is carbon paper having a microporous carbon gas diffusion layer coated with a copper catalyst rich in stepped surfaces.

[0026] In some embodiments, the anode is selected from one or more supported titanium fiber felts of platinum, iridium, ruthenium, and palladium, as well as their oxides or alloys.

[0027] Preferably, the anode is a titanium fiber felt sputtered with platinum.

[0028] In other embodiments, the anode may be a titanium fiber felt sputtered with iridium, ruthenium, and palladium, as well as their oxides or alloys.

[0029] In some other embodiments, the anode may be carbon paper supported by one or more of platinum, iridium, ruthenium, and palladium, as well as their oxides or alloys.

[0030] In some embodiments, the electrocatalytic CO2 reduction is carried out at a temperature of about 60°C or lower but above room temperature.

[0031] Preferably, the electrocatalytic CO2 reduction is carried out at approximately 60°C.

[0032] In some embodiments, the alkaline anion exchange membrane is an anion exchange membrane made of N-methylimidazolium-functionalized styrene polymer.

[0033] Preferably, the alkaline anion exchange membrane is an anion exchange membrane with a thickness of approximately 0.002 inches, made of N-methylimidazole functionalized styrene polymer.

[0034] In some embodiments, the acidic proton exchange membrane is a proton exchange membrane made of a tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer.

[0035] Preferably, the acidic proton exchange membrane is a proton exchange membrane made of tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer having a thickness of about 0.007 inches and an equivalent weight of about 1100 g / mol.

[0036] In some embodiments, the step-rich copper catalyst has a variable surface atomic coordination number of 4 to 9 at one or both of the Cu(111) and Cu(100) exposed surfaces.

[0037] In some embodiments, the copper catalyst rich in step surfaces has a variable surface tensile strain within 10% of its initial tensile strain, as measured at room temperature.

[0038] In some embodiments, at least six of the membrane electrode assemblies are stacked together.

[0039] In some embodiments, when a total current of 10 A is provided across the at least six membrane electrode assemblies via two conductive substrates sandwiching the stack, a Faraday efficiency of up to approximately 50% for the conversion of CO2 to C2H4 is achieved with a CO2 to C2H4 conversion efficiency of approximately 39%, and the stack of at least six membrane electrode assemblies has a total geometric area of ​​30 square centimeters.

[0040] In other embodiments, the total geometric area of ​​the one or more membrane electrode assemblies varies depending on the need for CO2 reduction, current density, size of the electrolytic cell, conductivity of the electrodes, membranes and their substrates, etc.

[0041] In some other embodiments, the electrolytic cell comprises a stack of multiple membrane electrode assemblies or a single membrane electrode assembly having a relatively large geometric area, or both.

[0042] Preferably, under industrially applicable continuous flow conditions, a stack of the multiple membrane electrode assemblies is chosen instead of the single membrane electrode assembly, because the stack configuration is relatively more flexible and easier to scale according to the amount of CO2 electrolysis power and compatibility with other equipment in the industrial plant or environment.

[0043] Another aspect of the present invention provides a method for manufacturing a membrane electrode assembly electrolysis system with pure water feed, the membrane electrode assembly electrolysis system being used for the electrocatalytic reduction of CO2 to C2H4 and C2H4 including ethanol, propanol and acetic acid. 2+ The compound, the membrane electrode assembly electrolysis system having a lifespan of at least 1000 hours, wherein the method comprises:

[0044] Provides copper catalysts with rich step surfaces;

[0045] Preparation of ink compositions containing copper catalysts rich in step surfaces;

[0046] A copper catalyst with a stepped surface is assembled on a support material to form a cathode;

[0047] Preparation of an anode-forming mixture for forming the anode;

[0048] An anode is formed by assembling an anode mixture on an anode carrier material;

[0049] An alkaline anion exchange membrane and an acidic proton exchange membrane are disposed between the cathode and the anode, wherein the alkaline anion exchange membrane is arranged to contact the cathode; the acidic proton exchange membrane is arranged to contact the anode; and the alkaline exchange membrane and the acidic proton exchange membrane are in contact with each other, thereby forming a multilayer structure of the membrane electrode assembly.

[0050] One or more membrane electrode assemblies are sandwiched between two conductive substrates;

[0051] Pure water is supplied as an electrolyte to a container containing one or more membrane electrode assemblies sandwiched between conductive substrates;

[0052] Power is supplied to the one or more membrane electrode assemblies via two conductive substrates;

[0053] Maintaining the electrolyte at a certain temperature ensures efficient electrocatalytic reduction of CO2 to C2H4 while preventing hydrogen evolution reaction from becoming the dominant reaction, and maintains stability for at least 1000 hours.

[0054] In some embodiments, the copper catalyst rich in step surfaces is provided in the following manner:

[0055] In an argon atmosphere, copper chloride and octadecylamine are dissolved in squalane at approximately 80°C for about 0.5 hours until a copper-based stock solution is formed.

[0056] Oleylamine and trioctylphosphine were mixed in an argon atmosphere and heated to approximately 200°C while being vigorously stirred to form a mixed solution.

[0057] The copper-based stock solution is injected into the mixed solution at approximately 200°C and maintained for approximately 5 hours to form a reaction mixture;

[0058] Allow the reaction mixture to cool naturally, centrifuge the cooled reaction mixture, and then wash it several times with an organic solvent; and

[0059] After washing, the supernatant was removed, and the particles were dried with argon at room temperature to obtain a solid copper catalyst rich in step surfaces.

[0060] In some embodiments, copper chloride and octadecylamine are dissolved in squalane in a weight ratio of approximately 1:2.

[0061] In some embodiments, oleylamine and trioctylphosphine are mixed in argon gas by heating at 200°C at a volume ratio of approximately 20:1.

[0062] In some embodiments, the organic solution used to wash the centrifuged and cooled reaction mixture is n-hexane.

[0063] In some embodiments, the cathode coated thereon with a copper catalyst rich in stepped surfaces is formed by the following steps:

[0064] A solid copper catalyst rich in step surfaces is dispersed in a mixed solution containing water, isopropanol and an alkaline ionomer solution.

[0065] The solid copper catalyst with a rich step surface was mixed with the mixed solution for about one hour by ultrasonic treatment until an ink composition containing the copper catalyst with a rich step surface was formed.

[0066] An ink composition containing a copper catalyst rich in step surfaces is coated onto carbon paper with a microporous carbon gas diffusion layer.

[0067] The carbon paper coated with a copper catalyst rich in step surfaces was dried in a vacuum for about one hour.

[0068] In some embodiments, the anode is formed from a titanium fiber felt supported by an anode-forming mixture comprising one or more of platinum, iridium, ruthenium, and palladium, as well as their oxides or alloys.

[0069] In some embodiments, the basic anion exchange membrane is selected from an anion exchange membrane made of N-methylimidazolium-functionalized styrene polymer and having a thickness of about 0.002 inches; the acidic proton exchange membrane is selected from a proton exchange membrane made of tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer and having a thickness of about 0.007 inches and an equivalent weight of 1100 g / mol.

[0070] In some embodiments, at least six of the membrane electrode assemblies are stacked on top of each other and sandwiched between two conductive substrates; the electrolyte temperature is maintained at approximately 60°C.

[0071] In some embodiments, the at least six membrane electrode assemblies have a total geometric area of ​​approximately 30 square centimeters.

[0072] The purpose of this section is to briefly introduce some concepts that will be further described in the "Detailed Description" section below. This section is not intended to identify key or essential features of the subject matter to be protected, nor is it intended to be used as an aid in determining the scope of the subject matter to be protected. Other aspects of the invention are disclosed in the embodiments described below. Attached Figure Description

[0073] This patent or application document contains at least one color drawing.

[0074] The same reference numerals in the accompanying drawings denote the same elements or elements that are functionally similar. The drawings include graphics of certain embodiments to further illustrate and clarify the above and other aspects, advantages, and features of the invention. It should be understood that these drawings only illustrate some embodiments of the invention and are not intended to limit the scope of the invention. The invention will now be described and explained with more features and details using the accompanying drawings, in which:

[0075] Figure 1A The stability of ECO2R to C2H4 production on a copper-based catalyst in a flow electrolyzer or MEA electrolyzer according to some embodiments of the present invention is shown in comparison with the stability of conventional systems according to some literature.

[0076] Figure 1B The results of a long-term stability test of ECO2R-to-C2H4 on SF-Cu in a MEA electrolyzer stack containing pure water feed and comprising six MEA electrolyzers, according to some embodiments of the present invention, are shown. The total cathode electrode area is set to 30 square centimeters and the reaction temperature is set to 60°C.

[0077] Figure 2A SEM images of SF-Cu catalysts according to some embodiments of the present invention are shown;

[0078] Figure 2B HRTEM images of SF-Cu according to some embodiments of the present invention are shown, revealing a large number of stacking faults (yellow rectangles marked with D);

[0079] Figure 2C HRTEM images of SF-Cu in some embodiments of the present invention are shown, revealing interlaced grain (twin) boundaries (yellow rectangles marked with E);

[0080] Figure 2D As shown Figure 2B The image shows an atomic resolution HAADF-STEM image of stacking faults in the selected region marked with D within the rectangular box shown; the yellow line highlights the stacking faults.

[0081] Figure 2E As shown Figure 2C The image shows an atomic resolution HAADF-STEM image of the twin boundary in the selected region marked E within the rectangular box shown; the yellow line highlights the quintuplet twin boundary.

[0082] Figure 2F Atomic resolution HAADF-STEM images of the surface steps of SF-Cu caused by stacking faults and twin boundaries are shown, where stacking faults and twin boundaries along the (111) plane are represented by white dashed lines;

[0083] Figure 2G This illustrates the use of a lattice far from defects as a reference (zero strain). Figure 2F The geometric phase analysis (GPA) strain map of tensile strain (ε) near the surface exit of stacked faults and twin boundaries is shown, where the measured tensile strain is perpendicular to the (111) plane, along which the stacked faults and twin boundaries are aligned with each other.

[0084] Figure 3 The in-situ heating characteristics of SF-Cu in different states are shown: (A and B) TEM images of pristine SF-Cu (before heating) and SF-Cu heated at 650 °C for 20 minutes (after heating); (C and D) HRTEM images of pristine SF-Cu (before heating) and SF-Cu heated at 650 °C for 20 minutes (after heating);

[0085] Figure 4 SEM images and size distributions of different catalyst nanoparticles are shown: (AC)SF-Cu; (DF)Cu-250; (GI)Cu-350; (JL)Cu-450;

[0086] Figure 5AX-ray absorption near-edge structure (XANES) spectra of SF-Cu, Cu-250, Cu-350, Cu-450 and standard copper foil references recorded at Cu K-edge are shown; values ​​are mean values; error bars represent standard deviations (n ​​= 3 repetitions);

[0087] Figure 5B Fourier transforms of the Cu K-edge EXAFS spectra of SF-Cu, Cu-250, Cu-350, Cu-450, and standard copper foil references are shown; values ​​are the mean; error bars represent the standard deviation (n = 3 repetitions);

[0088] Figure 5C The Faraday efficiency (FE) for ECO2R products on SF-Cu is shown in a flowing electrolytic cell with 1M potassium hydroxide as the electrolyte under a range of applied potentials; the values ​​are mean values; the error bars represent the standard deviation (n = 3 replicates);

[0089] Figure 5D The Faraday efficiency (FE) of SF-Cu, Cu-250, Cu-350, and Cu-450 for C2H4 is shown; the values ​​are the mean; the error bars represent the standard deviation (n = 3 repetitions);

[0090] Figure 5E The partial current density (J) of SF-Cu, Cu-250, Cu-350 and Cu-450 for C2H4 is shown; the values ​​are the mean; the error bars represent the standard deviation (n = 3 repetitions);

[0091] Figure 5F The tensile strain, coordination number (CN), and peak j are shown. C2+ The relationship between them; the value is the mean; the error bar represents the standard deviation (n = 3 repetitions);

[0092] Figure 6A The reaction scheme for ECO2R in a MEA electrolyzer with pure water feed containing AEM and PEM is schematically depicted according to some embodiments of the present invention.

[0093] Figure 6B The Faradaic efficiency (FE) for ECO2R products and the corresponding cell voltage without iR compensation are shown in an MEA electrolytic cell using pure water as the electrolyte under a range of applied current densities; platinum / titanium is used as the anode electrode and the reaction temperature is set at 60°C.

[0094] Figure 6C A schematic depiction of a MEA electrolyzer stack comprising six MEA electrolyzers for an ECO2R reaction according to some embodiments of the present invention is shown.

[0095] Figure 6D The stability monitoring of a MEA electrolyzer stack comprising six MEA electrolyzers according to some embodiments of the present invention is shown under a constant current of 10 amps, wherein the inset shows a digital photograph of the monitoring system;

[0096] Figure 7 X-ray diffraction (XRD) patterns of SF-Cu, Cu-250, Cu-350 and Cu-450 on carbon paper and bare carbon paper are shown.

[0097] Figure 8 The X-ray photoelectron spectroscopy (XPS) spectra of SF-Cu, Cu-250, Cu-350, and Cu-450 are shown: (A) Cu 2p XPS spectrum; (B) Cu LMM Auger spectrum; (C) O 1s XPS spectrum;

[0098] Figure 9 X-ray absorption (XAS) spectra of SF-Cu, Cu-250, Cu-350, and Cu-450, as well as standard copper foil, copper oxide, and cuprous oxide references, are shown: (A) Cu K-edge XAS spectrum; (B) Fourier transform of Cu K-edge extended X-ray absorption fine structure (EXAFS) spectrum;

[0099] Figure 10 The following are the Cu K-edge EXAFS fitting curves in R and q spaces: (A1-A2) copper foil reference; (B1-B2) SF-Cu; (C1-C2) Cu-250; (D1-D2) Cu-350; (E1-E2) Cu-450;

[0100] Figure 11 Two-dimensional plots of wavelet transform EXAFS (2D WT EXAFS) are shown: (A) Standard copper foil reference; (B) SF-Cu; (C) Cu-250; (D) Cu-350; (E) Cu-450; (F) Standard cuprous oxide reference; (G) Standard copper oxide reference;

[0101] Figure 12 The exposed surface of SF-Cu, determined by lead underpotential deposition (Pd-UPD), is shown.

[0102] Figure 13 Atomic models with different coordination numbers (CN) on Cu(111) are shown (side view, top view, and copper sites with different CN): (A) ideal Cu(111) with CN of 9; (BD) CN of 8, 7, and 6, respectively;

[0103] Figure 14Atomic models (side view, top view, and copper sites with different coordination numbers (CN)) are shown on Cu(111): (AF)CN are 7, 7, 6, 5, 5, and 5, respectively;

[0104] Figure 15 Atomic models with different coordination numbers (CN) on Cu(100) are shown (side view, top view, and copper sites with different CN): (A) ideal Cu(100) with CN of 8; (B and C) CN of 7 and 6, respectively;

[0105] Figure 16 Atomic models (side view, top view, and copper sites with different coordination numbers (CN)) are shown on Cu(100): (AD)CN are 6, 6, 5, and 4, respectively;

[0106] Figure 17 The total current density of ECO2R performed on SF-Cu at different applied potentials in a flow electrolytic cell using 1M potassium hydroxide as the electrolyte is shown; the values ​​are mean values; the error bars represent the standard deviation (n = 3 repetitions);

[0107] Figure 18 The performance of ECO2R on Cu-250 at different applied potentials in a flow electrolyzer using 1M potassium hydroxide as electrolyte is shown: (A) Faradaic efficiency (FE) for ECO2R products; (B) Total current density; values ​​are mean; error bars represent standard deviation (n = 3 replicates);

[0108] Figure 19 The performance of ECO2R on Cu-350 at different applied potentials in a flow electrolyzer using 1M potassium hydroxide as electrolyte is shown: (A) Faradaic efficiency (FE) for ECO2R products; (B) Total current density; values ​​are mean; error bars represent standard deviation (n = 3 replicates);

[0109] Figure 20 The performance of ECO2R on Cu-450 at different applied potentials in a flow electrolyzer using 1M potassium hydroxide as electrolyte is shown: (A) Faradaic efficiency (FE) for ECO2R products; (B) Total current density; values ​​are mean; error bars represent standard deviation (n = 3 replicates);

[0110] Figure 21 The comparison shows the total current density in SF-Cu, Cu-250, Cu-350 and Cu-450 used for ECO2R reaction in a flow electrolytic cell using 1M potassium hydroxide as electrolyte, under a certain range of applied potentials;

[0111] Figure 22 The results show the effects of C on SF-Cu, Cu-250, Cu-350, and Cu-450 substrates used for the ECO2R reaction in a flow electrolyzer using 1M potassium hydroxide as the electrolyte and at a range of applied potentials. 2+ Comparison of the Faraday efficiency (FE) and partial current density of the product: (A) for C 2+ The Faraday efficiency (FE) of the product; (B)C 2+ The partial current density;

[0112] Figure 23 The (A) strain, coordination number (CN), and peak value j of the ECO2R reaction are shown in a flow electrolyzer using 1M potassium hydroxide as the electrolyte. 乙烯 The relationship between (B) strain, coordination number (CN), and j 无氢气 The relationship between them;

[0113] Figure 24 The strain, coordination number (CN), and j are shown in a flow electrolyzer using 1M potassium hydroxide as the electrolyte at peak ECO2R performance. 氢气 The relationship between them;

[0114] Figure 25 SEM images (AC) and size distribution (D) of copper nanoparticles derived from oxides are shown.

[0115] Figure 26 The XRD patterns of SF-Cu on carbon paper, copper derived from oxides, and bare carbon paper are shown.

[0116] Figure 27 XPS spectra of copper derived from oxides are shown: (A) Cu 2p XPS spectrum; (B) Cu LMM Auger spectrum; (C) O 1s XPS spectrum;

[0117] Figure 28 The performance of ECO2R performed on copper derived from oxides in 1M potassium hydroxide at different applied potentials is shown: (A) Faraday efficiency (FE) for ECO2R products; (B) Total current density; values ​​are mean; error bars represent standard deviation (n = 3 replicates);

[0118] Figure 29 The comparison of total current density in SF-Cu and oxide-derived copper used for the ECO2R reaction is shown in a flow electrolytic cell using 1M potassium hydroxide as the electrolyte, under a range of applied potentials.

[0119] Figure 30The performance of ECO2R performed on SF-Cu and oxide-derived copper in a flowing electrolytic cell using 1M potassium hydroxide as the electrolyte is compared within a range of applied potentials: (A and C) for C 2+ Comparison with the Faraday efficiency (FE) of C2H4; (B and D) C 2+ Comparison with the partial current density of C2H4;

[0120] Figure 31 The performance of ECO2R in a flowing electrolyzer using 1M phosphoric acid on SF-Cu and SF-Cu / PMMA is shown: (A) Faradaic efficiency (FE) and total current density on SF-Cu with only hydrogen gas and no ECO2R products at a range of applied potentials; (B) Faradaic efficiency (FE) and total current density on SF-Cu / PMMA with only hydrogen gas and no ECO2R products at a range of applied potentials, wherein 1M phosphoric acid (H3PO4) is used as the electrolyte; values ​​are mean values ​​and error bars represent standard deviations (n ​​= 3 replicates); (C) SEM image of the surface of SF-Cu / PMMA; (D) SEM image of the cross section of SF-Cu / PMMA.

[0121] Figure 32 The performance of ECO2R performed on SF-Cu / PMMA in a flow electrolyzer using 1M phosphoric acid containing 3M potassium chloride as the cathode electrolyte and 1M phosphoric acid as the anode electrolyte is shown: (A) the Faradaic efficiency (FE) for ECO2R products over a range of applied potentials; (B) the corresponding total current density over a range of applied potentials; values ​​are mean; error bars represent standard deviations (n ​​= 3 repetitions);

[0122] Figure 33 The performance of ECO2R performed on SF-Cu / PMMA in a flow electrolyzer using 1M phosphoric acid containing 3M potassium iodide as the cathode electrolyte and 1M phosphoric acid as the anode electrolyte is shown: (A) the Faradaic efficiency (FE) of the ECO2R product over a range of applied potentials; (B) the corresponding total current density over a range of applied potentials.

[0123] Figure 34 A digital photograph of the flow channel is shown after approximately 10 minutes of ECO2R reaction on SF-Cu in an MEA electrolytic cell using 1M phosphoric acid containing 3M potassium nitrate (KNO3) as the anolyte.

[0124] Figure 35The performance of ECO2R performed on SF-Cu in a MEA electrolyzer using 1M potassium hydroxide as the anolyte is shown: (A) the Faradaic efficiency (FE) of the ECO2R products over a range of applied potentials; (B) the corresponding total current density over a range of applied potentials.

[0125] Figure 36 The performance comparison of ECO2R on SF-Cu in a MEA electrolyzer using 1M potassium hydroxide / pure water as the anolyte is shown under a range of applied potentials: (A, C, and E) show the performance of ECO2R on C2H4 and C2Cu under a range of applied potentials. 2+ A comparison of the Faraday efficiency (FE) of all ECO2R products; (B, D, and F) show the Faraday efficiency of C2H4, C... 2+ Comparison of partial current densities with all ECO2R products; the reaction temperature of the ECO2R reaction under pure water conditions is 60℃, while other ECO2R reactions are carried out at room temperature;

[0126] Figure 37 A MEA electrolyzer stack comprising six repeating MEA electrolyzers for carrying out an ECO2R reaction is schematically depicted according to some embodiments of the present invention.

[0127] Figure 38 The stability of ECO2R to C2H4 production on SF-Cu at a cell voltage of 3.2 volts in an MEA electrolyzer using 1M potassium hydroxide as the anolyte, according to some embodiments of the present invention, is shown.

[0128] Figure 39 The following are in-situ XRD measurements of SF-Cu after a 10-hour ECO2R reaction in 0.1 M potassium hydroxide at a 4 V electrolytic cell voltage: (A) total current density; (B) in-situ XRD pattern, compared with... Figure 39 (A) Corresponds;

[0129] Figure 40 The following are in-situ XRD measurements of SF-Cu subjected to an ECO2R reaction in 0.1 M KOH at a step electrolytic cell voltage for 8 hours: (A) total current density; (B) in-situ XRD pattern, compared with... Figure 40 (A) Corresponds;

[0130] Figure 41The following diagram illustrates the ECO2R mechanism determined by DFT calculations and experiments, as well as the effects of coordination number (CN) and tensile strain on ECO2R: (A) In-situ Raman spectra of ECO2R performed on SF-Cu for 1 hour in a custom flow electrolyzer with a dual-electrode system at a cell voltage of 4 volts, according to some embodiments of the invention; (B) and (C) show the Faradaic efficiency (FE) and partial current density for C2H4 on SF-Cu used for ECO2R and ECOR reactions, respectively, at a range of applied potentials in 1M potassium hydroxide; (D) Reaction energy diagrams of ECO2R to C2H4 produced via direct hydrogenation of *CO to *CHO followed by dimerization of unoccupied *CO with *CHO, in ideal copper and SF-Cu models.

[0131] Figure 42 The reaction energy diagrams for the conversion of ECO2R to the *CO intermediate are shown in the ideal copper and SF-Cu models;

[0132] Figure 43 In-situ Raman measurements of SF-Cu used for the ECO2R reaction in 0.1 M potassium hydroxide at different electrolytic cell voltages are shown.

[0133] Figure 44 The total current density of SF-Cu used for the ECO2R reaction is shown in an in-situ Raman measurement at a cell voltage of 4 volts in a flowing electrolyzer using 0.1 M potassium hydroxide.

[0134] Figure 45 The results of in-situ Raman measurements of SF-Cu used for the ECO2R reaction are shown in a flowing electrolyzer using 0.1 M potassium hydroxide at a cell voltage of 6 V; (A) total current density; (B) in-situ Raman spectrum over 1 hour;

[0135] Figure 46 The performance of ECOR performed on SF-Cu in a flowing electrolyzer using 1M potassium hydroxide as the electrolyte is shown, along with a comparison with ECO2R performance: (A) Faradaic efficiency (FE) for ECOR products at a range of applied potentials; (B) Total current density for ECOR at a range of applied potentials; (C) and (D) respectively show the performance of ECOR on SF-Cu for ECO2R and ECOR at a range of applied potentials in 1M potassium hydroxide. 2+ A comparison of Faraday efficiency (FE) and partial current density;

[0136] Figure 47The reaction energies of ECO2R are shown in the ideal copper and SF-Cu models via the direct hydrogenation of *CO to *CHO followed by dimerization of unoccupied *CO and *CHO, ECO2R via the direct hydrogenation of *CO to *COH followed by dimerization of unoccupied *CO and *COH, and ECO2R via the hydrogenation of 2*CO to 2*CHO followed by dimerization of *CHO.

[0137] Figure 48 Temperature programmed desorption (TPD) of (A) CO2 and (B) carbon monoxide on SF-Cu, Cu-250, Cu-350 and Cu-450 is shown.

[0138] Those skilled in the art will understand that the elements in the accompanying drawings are shown for the purpose of simplicity and clarity and are not necessarily drawn to scale. Detailed Implementation

[0139] It will be apparent to those skilled in the art that various modifications, including additions and / or substitutions, can be made without departing from the scope and spirit of the invention. Specific details may be omitted so as not to obscure the invention; however, the purpose of this disclosure is to enable those skilled in the art to practice the teachings herein without having to perform excessive experimentation.

[0140] Please go to Figure 1A and 1B Under normal alkaline conditions (1M potassium hydroxide), in a flowing electrolyzer at approximately -0.58 V (all values ​​are relative to the reversible hydrogen electrode (RHE) throughout the text unless otherwise stated), the SF-Cu catalyst for the production of C2H4 from ECO2R exhibits a Faradaic efficiency (FE) of approximately 80% and a partial current density of 568 mA / cm². 乙烯 The excellent ECO2R properties of SF-Cu are clearly correlated with its coordination number (CN) and tensile strain. Figure 5F , 23 (and 41). To eliminate the formation and permeation of carbonates in the alkaline electrolyte, the ECO2R reaction was subsequently carried out in a flowing electrolytic cell using a strong acid as the electrolyte; however, this strong acid system was not suitable for the more promising MEA electrolytic cell architecture in industry. Finally, pure water was used as the electrolyte to carry out ECO2R to C2H4 / C in a MEA electrolytic cell assembled with AEM and PEM. 2+Compounds. Under pure water conditions, with an electrolytic cell voltage of approximately 4.3 volts and no iR compensation, the SF-Cu electrocatalytic CO2 reduction to ethylene exhibits a Faradaic efficiency (FE) of approximately 42% and a total current density of 300 mA / cm². Furthermore, ECO2R was scaled up in a stack of six MEA electrolytic cells with a pure water feed. At a total current of 10 amps, the FE of the SF-Cu electrocatalytic CO2 reduction to C2H4 reached approximately 50%, and the CO2 to C2H4 conversion rate was as high as approximately 39%. This MEA electrolytic cell stack system was able to operate stably for over 1000 hours, exceeding that of conventional ECO2R systems for C2H4 production.

[0141] Please go to Figures 2A-2E First, SF-Cu nanoparticles with an average diameter of approximately 60 nanometers were prepared. Figure 2A Detailed preparation methods for SF-Cu nanoparticles can be found in some of the embodiments described below. High-resolution transmission electron microscopy (HRTEM) and aberration-corrected high-angle annular dark-field scanning TEM (HAADF-STEM) images of SF-Cu nanoparticles reveal numerous intersecting stacking faults. Figure 2B and 2D ). Figure 2C Selected regions (marked E) in the HRTEM images reveal numerous interlaced grain boundaries in SF-Cu, including ∑3 coincident lattice (CSL) grain boundaries, and the formation of some typical fivefold twin structures (in Figure 2E The twin boundaries (highlighted in yellow in the HAADF-STEM image shown) can induce intrinsic stresses, especially large tensile strains / stresses on the surface. Figure 2G The GPA plot shown reveals localized tensile strain of up to approximately 0.8% around the surface ports of twin boundaries and stacking faults. Figure 2F As shown, step surfaces are induced at the surface ports of twin boundaries and stacking faults, resulting in a decrease in the coordination number of surface copper atoms. Typically, high surface tensile strain and low CN lead to the formation of high-energy active surfaces that are conducive to catalytic reactions. Therefore, the abundant stacking faults and grain boundaries in SF-Cu contribute to the superior ECO2R performance of this invention.

[0142] To verify the impact of these structures on ECO2R performance, SF-Cu was calcined at different high temperatures (250, 350, and 450 °C; Cu-250, Cu-350, and Cu-450) to alter their microstructure. Theoretically, high-temperature treatment leads to atomic rearrangement to achieve a more thermodynamically favorable state, minimizing the total surface energy. The effect of calcination on SF-Cu in this invention has been clearly demonstrated by in-situ heated TEM images, proving that stacking faults and twin boundaries in SF-Cu decrease or even disappear at high temperatures. Figure 3 After each high-temperature treatment, there was no perceptible change in the sample size distribution. Figure 4 All samples remained metallic copper (as revealed by the XRD pattern on the carbon paper in Figure 7). X-ray photoelectron spectroscopy (XPS) measurements showed slight oxidation on the surface of all samples. Figure 8 Cu K-Edge X-ray absorption spectroscopy (XAS) can be used to study the local coordination of copper in SF-Cu. Figure 9-11 (Table 1). Figure 5A X-ray absorption near-edge structure spectroscopy (XANES) measurements confirmed that all samples contained almost a pure metallic copper phase. Furthermore, the Fourier transform χ(R) function of the extended X-ray absorption fine structure (EXAFS) data in the frequency domain (R) revealed that CN increases with increasing calcination temperature. Figure 5B ).exist Figure 5F The structural parameters obtained from the EXAFS fitting results further indicate that the CN of copper gradually increases (from approximately 7.6 to 9.9), and the tensile strain gradually decreases in the order of SF-Cu, Cu-250, Cu-350 and Cu-450 (Table 1) (from approximately 1.03% to 0.28%), which is consistent with the observed stacking faults and twin boundaries characterized by in-situ heated TEM as described above.

[0143] Table 1

[0144]

[0145]

[0146] CN: coordination number; R: bond length; σ: Debye-Waller factor.

[0147] To verify the possibility of low CN on the surface copper atoms, lead underpotential deposition (lead UPD) was first used to identify the exposed surfaces of SF-Cu (i.e., Cu(111) and Cu(100)). Figure 12 Subsequently, atomic structure simulations were performed to reveal the possible CN (copper atoms) on the exposed surfaces (111 and 100) of SF-Cu. Figure 13-16The CN of a perfect Cu(111) surface is 9 ( Figure 13 A), other CNs (8, 7, 6, and 5) are also possible, depending on the different slip patterns ( Figure 13 B-13D and Figure 14 A-14F). Similarly, a perfect Cu(100) surface contains surface atoms with a CN of 8 ( Figure 15 A), and atomic sites with lower CN include 7, 6, 5, and 4 ( Figure 15 (B-15C and 16A-16D). Therefore, the large number of stacking faults and cross-grain boundaries result in a CN range of 9 to 4 for copper atoms on the SF-Cu surface.

[0148] Under 1M potassium hydroxide electrolyte conditions, SF-Cu exhibited the best ECO2R performance and the highest C2H4 and C2C values ​​in a flowing electrolytic cell among all samples. 2+ Faraday efficiency (FE) Figure 5C and Figure 17-20 Specifically, for SF-Cu, the peak FE for C2H4 is as high as approximately 80% at around -0.58 volts, at which voltage j 乙烯 The energy efficiency (EE) of the C2H4 semi-electrolyte reaches approximately 568 mA / cm². 半电解池 The percentage was as high as approximately 51%. As the processing temperature increased, the samples showed a significant decrease in ECO2R activity. Figure 21 This effect applies to the ECO2R process of C2H4 / C. 2+ Clearly, this is likely due to the higher CN and lower tensile strain at high temperatures. Figure 5D , Figure 5E and Figure 22 These results preliminarily demonstrate the structure-property relationship between CN, tensile strain, and ECO2R properties. Figure 5F In the figure, due to atomic rearrangement, tensile strain and CN exhibit a strong linear correlation with calcination temperature (black line). More importantly, as CN decreases and tensile strain increases, the partial current density (j C2+ j 乙烯 or j 无氢气 , where "j 无氢气 "Refers to the partial current density of all ECO2R products) increasing monotonically ( Figure 5F and Figure 23 That is, the partial current density (j) C2+ j 乙烯 or j 无氢气 The function of tensile strain and CN exhibits a strong linear correlation. However, the function of tensile strain and CN shows a weak correlation with the partial current density of the competing response (j 氢气 It exhibits low linear correlation. Figure 24).

[0149] In addition, in order to exclude the oxidized state (Cu) + / Cu 2+ The effect of ) on ECO2R performance was investigated, and oxide-driven copper based on SF-Cu was prepared and characterized. Figures 25-27 Compared to SF-Cu, oxide-driven copper shows almost no improvement in ECO2R performance in terms of Faraday efficiency (FE) or current density. Figures 28-30 This indicates that, in this invention, oxide-driven copper (or its oxidation state) is not the key factor determining ECO2R performance. After excluding the convolution effects of sample size, crystal structure, and copper oxidation state... Figure 4 , Figure 7 and Figure 30 The results showed that the low CN and high tensile strain in SF-Cu were clearly associated with high ECO2R activity.

[0150] Carbonate formation caused by alkaline and neutral electrolytes such as potassium hydroxide and potassium bicarbonate used in ECO2R is detrimental to the stability of the gas diffusion electrode (GDE) and the electrolysis system. Some previous studies have proposed strategies to eliminate carbonate formation, but these strategies result in significant energy consumption / loss. Therefore, based on high-performance SF-Cu, through cations (such as potassium ions (K...)... + An expansion strategy was proposed for electrocatalytic CO2 reduction in a strongly acidic mobile phase electrolyzer equipped with PEM (Nafion 117) to improve the reaction kinetics of ECO2R under acidic conditions.

[0151] Initially, SF-Cu GDE was used directly as the cathode in a flowing electrolyzer with 1M phosphoric acid as the electrolyte for ECO2R. No ECO2R products were observed other than hydrogen. Figure 31 (A)). Therefore, a buffer layer is assembled on SF-Cu GDE to slow down the diffusion of hydroxide and potassium ions from the SF-Cu surface outward, thereby enriching the potassium ion concentration and increasing the local pH on the surface. Figure 31 C and Figure 31 D). The buffer layer can be a cross-linked microporous polymethyl methacrylate (PMMA) layer (SF-Cu / PMMA). However, SF-Cu / PMMA did not exhibit selectivity for ECO2R products. Figure 31 B). According to the cation enhancement strategy, when using 1M phosphoric acid containing a high concentration of potassium ions (3M potassium chloride) as the cathode electrolyte and 1M phosphoric acid as the anolyte, SF-Cu / PMMA exhibits approximately 40% C at -1.2 V. 2+FE (approximately 28% for C2H4, approximately 10% for ethanol (C2H5OH), and approximately 2% for acetic acid (CH3COOH)) Figure 32 A) and a total current density of approximately 360 mA / cm². Figure 32 B). When using potassium iodide instead of potassium chloride as the potassium ion source, at -1.1 volts, C 2+ FE is increased to approximately 48% (approximately 33% for C2H4, approximately 14% for ethanol (C2H5OH), and approximately 1% for acetic acid (CH3COOH)). Figure 33 A), the total current density is approximately 345 mA / mm². Figure 33 B). In summary, due to its improved morphology and structure, SF-Cu exhibits better performance against C2H4 and C2H4 compared to other acidic systems (e.g., the acidic systems disclosed in Huang et al. (2021) (Table 2)). 2+ Higher FE and lower activation overpotential

[0152] Table 2:

[0153]

[0154]

[0155]

[0156] a. A small percentage of propanol was not calculated. b. The denominator is the area of ​​the electrode.

[0157] x. The area of ​​the electrode is not specified.

[0158] c. Current density is not missing.

[0159] -.none

[0160] Considering practical feasibility, the ECO2R reaction based on SF-Cu was carried out in an acidic MEA electrolyzer equipped with Nafion membranes, which is more suitable for industrial applications. This was done to enrich potassium ions (K+) on the SF-Cu surface. + A 1M phosphoric acid solution containing 3M potassium nitrate was used as the anolyte. Under the influence of an electric field, potassium ions and hydrogen ions / hydrated hydrogen ions in the anolyte pass through the Nafion membrane to the SF-Cu surface. Ideally, potassium ions promote ECO2R, while hydrogen ions / hydrated hydrogen ions act as a proton source. Although some ECO2R products, such as carbon monoxide and ethylene, were formed during the initial test, the ECO2R reaction stopped after a few minutes, and the hydrogen evolution reaction (HER) became dominant. This is because the continuous potassium ion flow from the anode to the cathode leads to severe carbonate precipitation in the cathode channel, thus hindering CO2 mass transfer. Figure 34 To address this issue, pure water is used as the electrolyte for the ECO2R reaction in the MEA electrolyzer of this application. The main challenges in using a pure water MEA electrolyzer for electrocatalytic CO2 reduction are maintaining a high local pH on the cathode catalyst surface to ensure efficient ECO2R reaction, and the need for PEM (particulate metallization) to handle the transport of protons generated during electrolysis. Based on these issues, an AEM (alcoholic emulsion) layer is added between the cathode and the PEM. Figure 6A In forward bias mode, water, acting as a proton source, participates in the ECO2R reaction at the cathode and is oxidized into oxygen at the anode. Figure 6C The remaining hydroxide ions at the cathode and the remaining hydrogen ions at the anode will pass through AEM and PEM respectively, forming water at the interface of AEM and PEM (chemical formulas (3)-(5)), which can effectively increase the local pH on the surface of the cathode catalyst. Although a small amount of CO2 may dissolve in pure water to form carbonic acid (chemical formula (6)), the alkaline AEM and acidic PEM will effectively inhibit the formation of carbonic acid and shift the equilibrium reaction to the left.

[0161] Cathode: 2CO2 + 8H2O + 12e - →C2H4+12OH - (3)

[0162] Anode: 6H₂O → 3O₂ + 12H₂O + +12e - (4)

[0163] Interface: 12OH - +12H + →12H2O (5)

[0164] CO2 dissolution:

[0165] Furthermore, since there are no cations at the cathode to maintain the electroneutrality of pure water, CO2 cannot react with electroinduced hydroxide ions to form carbonates, thus eliminating carbonate permeation issues. Water can pass through both the AEM and PEM; therefore, water as a proton source is sufficient for the cathode reduction reaction.

[0166] In some implementations, when the total cathode electrode area is approximately 30 square centimeters, the CO2 inlet flow rate will be approximately 30 sccm.

[0167] In some implementations, all ECO2R reactions are carried out at a reaction temperature of approximately 60°C, and titanium fiber felt treated with platinum (platinum / titanium) sputtering is selected as the anode electrode.

[0168] In some implementations, Sustainion X37-50 is selected as the AEM and Nafion 117 is selected as the PEM for the electro-induced hydroxide and hydrogen ion exchange membranes, respectively.

[0169] In other embodiments, a bipolar film can be used as the AEM / PEM.

[0170] Preferably, when assembling the MEA electrolyzer system of this application, Sustainion X37-50 and Nafion 117 are selected as AEM and PEM, respectively, instead of bipolar membranes.

[0171] In some embodiments, the MEA electrolytic cell system of this application includes a cathode selected from SF-Cu GDE and an anode selected from titanium fiber felt treated with platinum (platinum / titanium) sputtering, wherein a combination of AEM and PEM separates the cathode and anode, such that the cathode is in contact with the AEM and the anode is in contact with the PEM.

[0172] To reduce the activation overpotential of pure water, the MEA electrolyzer of this application conducts the ECO2R reaction at a certain temperature and in constant current mode, thereby continuously inhibiting HER. In some embodiments, the temperature sufficient to induce ECO2R in constant current mode without allowing HER to dominate is approximately 60°C. Figure 6B ).

[0173] exist Figure 6B At a total current density of 300 mA / mm², the ECO2R selectivity reaches a peak of approximately 66% FE, including for C. 2+ The electrolyte contains approximately 52% FE (approximately 43% ethylene FE, approximately 6% ethanol FE, approximately 2% propanol (CH3CH2CH2OH) FE, and approximately 1% acetic acid FE). The cell voltage without iR compensation is approximately 4.3 volts. Excluding the energy consumed by the reaction temperature, the proposed pure water-feed MEA electrolyzer architecture provides an overall electrolyzer energy conversion efficiency (EEE) of approximately 18.2%. 全电解池 Product analysis shows that, in the proposed pure water-feed MEA electrolysis system, the peak FE and partial current density of the ECO2R product are even comparable to the corresponding values ​​in a MEA electrolysis cell using 1M potassium hydroxide as the electrolyte. Figure 35 (and Figure 36). MEA electrolyzers fed with pure water can circumvent the theoretical CO2 utilization limit of the ECO2R reaction by completely eliminating the formation and permeation of carbonates.

[0174] Considering the excellent ECO2R performance of SF-Cu in the proposed pure water-feed MEA electrolyzer system, a MEA electrolyzer stack system containing six MEA electrolyzers was assembled and tested. Figure 6C and Figure 37 To evaluate its durability and practicality. At a total current of 10 amps, six groups of SF-Cu GDE with a total geometric area of ​​30 square centimeters provide approximately 50% of the FE for ethylene. Figure 1B Without iR compensation, the stack system remained stable for over 1000 hours at a stack voltage of 25 to 27 volts (the voltage of each MEA electrolyzer group was approximately 4.4 V, as shown in Figure 6D). In contrast, the stability of ECO2R on SF-Cu in MEA electrolyzers under alkaline conditions was even shorter than 4 hours. Figure 38 The 6-MEA electrolyzer stack system was able to provide a CO2 to C2H4 conversion rate of up to approximately 39%, and no electrolyte overflow from the GDE was observed after 1000 hours of operation. This significant difference in performance is likely due to the increased reaction temperature (approximately 60°C), which allows water accumulated on the GDE to be discharged with steam more quickly.

[0175] In some implementations, the pure water-feed MEA electrolyzer stack system also incorporates an integrated circuit for monitoring the ECO2R reaction, for example... Figure 6D The illustration shows the Arduino development board. Throughout the 1000-hour measurement period, except for some voltage fluctuations in the first 100 hours, each electrolyzer in the system exhibited almost identical voltages, demonstrating the possibility of achieving industrial-level stable ECO2R using the MEA electrolyzer stack.

[0176] Furthermore, in-situ X-ray diffraction (XRD) measurements were performed in a flow electrolyzer with a dual-electrode system to evaluate the stability of the SF-Cu catalyst, and the results are as follows: Figure 39 As shown. The crystal structure of SF-Cu was proven to be stable during the ECO2R reaction under different electrolytic cell voltages. Figure 39 and Figure 40 In summary, SF-Cu exhibits superior overall ECO2R performance for C2H4 production in flowing electrolyzers, MEA electrolyzers, and MEA electrolyzer stacks compared to most reported performance in basic, neutral, and acidic ECO2R systems. Figure 1A (See Table 2). More importantly, the stability of the pure water-feed MEA system exceeding 1000 hours will take ECO2R technology a step closer to industrial levels.

[0177] Please go to Figures 41-48The superior ECO2R C2H4 production performance of SF-Cu and the ECO2R reaction pathway was demonstrated by density functional theory (DFT) calculations and in-situ and ex-situ measurements, which showed that the superior performance of SF-Cu in pure water systems is attributed to the combination of this novel electrolytic architecture with the excellent catalytic activity resulting from the low coordination number (CN) and high tensile strain of SF-Cu.

[0178] In this application, DFT calculations were performed on ideal Cu(111) and SF-Cu(111) models to reveal the superior ECO2R to C2H4 production properties of SF-Cu. To amplify the influence trends of CN and tensile strain, the cell of the SF-Cu model was expanded by a factor of 1.1, implying a 10% tensile strain, and the CN of the SF-Cu model was set to 7. The reaction energy of CO2 to *COOH on the SF-Cu surface is 0.39 eV ( Figure 42 The reaction energy is much lower than that of ideal copper (0.75 eV). Subsequently, due to the negative reaction energy of ideal copper and the SF-Cu model, *COOH is readily converted to *CO. As described in this paper, the *CO intermediate of ECO2R on SF-Cu was observed by in-situ Raman measurements at different potentials. Figure 41 A and Figures 43-45 Located at 270-360 cm. -1 The peak values ​​within this range are related to suppressed rotation and stretching of Cu-CO. In the 1900–2200 cm⁻¹ range... -1 The peak at this point may be attributed to the C≡O stretching of surface-adsorbed CO, including top-bonded CO and bridge-bonded CO. CH vibrations were also observed in the 2700–3000 cm⁻¹ region, which may originate from hydrogenation intermediates (e.g., *CHO, *COCHO, etc.). Due to the complexity of ECO₂R hydrogenation intermediates, more precise attribution of these peaks is very challenging.

[0179] The general assumption is that CC coupling begins with *CO. However, the subsequent dimerization reaction has not been confirmed. If the dimerization of *CO to *OCCO is considered the main pathway for CC coupling, then the direct electrocatalytic reduction of CO (ECOR) to C2H4 / C on SF-Cu could be a significant factor. 2+ j 乙烯 / j C2+ (Productivity) should be higher than that of ECO2R reduction of ethylene / C 2+ j 乙烯 / j C2+ (Productivity). To verify this hypothesis, direct *CO dimerization was demonstrated by performing ECOR on SF-Cu. If the hypothesis is verified, then it is expected that for C2H4 / C 2+ j 乙烯 / jC2+ It will be higher than ECO2R. Interestingly, for direct ECOR, SF-Cu shows a lower j 乙烯 / j C2+ ( Figure 41 B. Figure 41 C and Figure 46 This indicates that *CO dimerization to *OCCO may not be the primary CC coupling pathway for ECO2R on SF-Cu. Then, the two hydrogenation pathways of *CO (*CO to *CHO and *CO to *COH) were calculated. Figure 47 The hydrogenation energy of *CO to *CHO is lower than that of *CO to *COH. Figure 41 D shows that the reaction energy of SF-Cu hydrogenating *CO to *CHO decreases from 0.56 eV to 0.30 eV. Figure 41 D). Therefore, this application proposes two possible pathways: hydrogenation of unoccupied *CO to *CHO to form 2*CHO (*CHO + *CHO), and direct coupling of unoccupied *CO and *CHO to form *COCHO. The formation of two *CHO on ideal copper and SF-Cu requires a very high uphill reaction energy ( Figure 47 This indicates that CC coupling via *CHO dimerization is unfavorable. In contrast, coupling of *CO and *CHO requires lower reaction energies, and the reaction energy (0.77 eV) for *CO and *CHO coupling to form *COCHO at the SF-Cu surface is lower than that for ideal copper (0.88 eV). For both ideal copper and SF-Cu, the subsequent hydrogenation of *COCHO to *COCH2O is exothermic. Therefore, hydrogenation of *CO to *CHO, followed by coupling of unoccupied *CO and *CHO to *COCHO to *COCH2O, should be the most favorable pathway for C2H4 formation. Density functional theory (DFT) results show that, thermodynamically, SF-Cu is more readily electrocatalytically reduced from CO2 to C2H4 than ideal copper.

[0180] Furthermore, programmed temperature desorption (TPD) measurements of CO2 and carbon monoxide showed that the CO2 / CO adsorption capacity of the samples decreased with increasing processing temperature (SF-Cu>Cu-250>Cu-350>Cu-450). Figure 48 Surface copper atoms with lower CN tend to bind / adsorb more CO2 / carbon monoxide to compensate for the lack of coordination, which will accelerate the ECO2R reaction kinetics. It should be believed that the above-mentioned thermodynamic and kinetic advantages are attributable to the effects of the low CN and high tensile strain of SF-Cu.

[0181] According to various embodiments of the present invention, it is evident that abundant stacking faults and grain boundaries are associated with low CN and high tensile strain in SF-Cu, thereby producing a high-energy active surface for ECO2R to C2H4. This indicates that lower CN and higher tensile strain are associated with higher ECO2R activity. Based on the current SF-Cu and the proposed MEA electrolysis architecture, the ECO2R reaction can proceed efficiently under pure water conditions, eliminating carbonate formation and permeation, thus overcoming the theoretical limitations of CO2 utilization and extending the stability of the ECO2R system. Furthermore, scale-up ECO2R in a pure water-feed MEA electrolyzer stack has been demonstrated. At a total current of 10 amps, the CO2 to C2H4 conversion rate is approximately 39%, achieving up to 50% FE for ethylene, and the system exhibits stability with a constant output exceeding 1000 hours. In some embodiments, to further improve the system's energy efficiency, product selectivity can be increased, and its operating voltage can be reduced. It is believed that the pure water-feed ECO2R technology under the proposed MEA architecture has injected new vitality.

[0182] Example

[0183] (A) Chemical reagents

[0184] Deuterium oxide (D₂O, 99.9 at.% D, 151882), sodium 3-(trimethylsilane)propionic acid-2,2,3,3-d⁴ acid (TSP, ≥98.0% (NMR), 269913), Nafion TM Solution (5 wt%, 274704), polytetrafluoroethylene formulation (60% PTFE aqueous solution, 665800), oleylamine (70%, O7805), copper chloride (I) (CuCl, 97%, 212946), n-hexane (C6H) 1499%, HX0293), octadecylamine (≥99%, 305391), trioctylphosphine (90%, 117854), squalane (96%, 234311), potassium hydroxide (KOH, 99.99%, 306568), phosphoric acid (H3PO4, 85%, 345245), potassium nitrate (KNO3, 99.0%, 221295), lead(II) nitrate (Pb(NO3)2, ≥99%, 228621), potassium iodide (KI, 99%, 221945), and potassium chloride (KCl, 99.0-100.5%, P3911) were purchased from Sigma Aldrich. Potassium hydroxide (KOH, ≥85.0%), nickel foam (2 mm thick, 99.9%), and titanium fiber felt (0.25 mm thick, 99.9%) were purchased from Sinopharm Chemical Reagent Co., Ltd. (China). Nitric acid (HNO3, pH = -1.0, 70%, A200) and isopropanol (C3H8O, IPA, ≥99.5%, 3776) were purchased from Fisher Scientific. Anion exchange membrane (Fumasep FAA-3-PK-75), gas diffusion layer (carbon paper, GDE, Sigrette 39BB), and... 117 membrane (591239) was purchased from FuelCell Store. Alkaline ionomer solution (5% ethanol solution, Sustainion XA-9) and anion exchange membrane (Sustainion X37-50) were purchased from Dioxide Materials.

[0185] (B) Catalyst Preparation

[0186] In a typical synthesis, 0.05 g of copper chloride and 0.1 g of octadecylamine were dissolved in 1 mL of squalane at 80 °C under argon atmosphere and maintained at this temperature for 0.5 h to form a copper-based stock solution. 10 mL of oleylamine and 0.5 mL of trioctylphosphine were added to a flask and heated to 200 °C under strong magnetic stirring under argon atmosphere. The copper-based stock solution was then rapidly injected into the aforementioned 200 °C oleylamine solution and maintained at this temperature for 5 h. After natural cooling, the resulting sample was collected by centrifugation and washed several times with n-hexane. Finally, the sample was dried under argon gas at room temperature. Because the sample has a stepped surface, it is designated as SF-Cu.

[0187] To investigate the structure-activity relationship of SF-Cu for electrocatalytic CO2 reduction, SF-Cu samples were calcined in a tube furnace at different temperatures (250 °C, 350 °C, and 450 °C; Cu-250, Cu-350, and Cu-450) in a mixed gas environment (hydrogen / argon: 5 v / v%; 200 sccm (standard cubic centimeters / min)) for 2 hours to prevent oxidation. Furthermore, copper derived from the oxide was prepared by directly calcining SF-Cu in air at 450 °C for 2 hours.

[0188] (C) Fabrication of Gas Diffusion Electrode (GDE)

[0189] For measurements in a flow electrolyzer and MEA electrolyzer under alkaline conditions, a cathode GDE was prepared on conventional carbon paper. The catalyst was dispersed in a mixed solution containing water, IPA (1:4 v / v), and some alkaline ionomer solution (5 wt% vs. catalyst, Sustainion XA-9) by ultrasonic treatment for 1 hour to form a catalyst ink of 1 mg / mL. The ink was then used to measure the catalyst concentration at approximately 1 mg / mL. 2 GDEs were fabricated by spraying a loading amount onto carbon paper with a microporous carbon gas diffusion layer, and then drying them in a vacuum at 120°C for 1 hour before use (SF-Cu GDE). x and RuO x A mixture of supporting carbon paper.

[0190] For measurements in flow electrolyzers and MEA electrolyzers under acidic conditions: using Nafion TM Solution replaces alkaline ionomer. A PTFE solution containing PMMA is sprayed onto an SF-Cu GDE as the cathode GDE (SF-Cu / PMMA), and a platinum-supported titanium fiber felt (platinum / titanium) mixture is used as the anode electrode. The process is carried out in an argon atmosphere (5 × 10⁻⁶) using a magnetron sputtering system. -3 Platinum was sputtered onto titanium fiber felt using a pure platinum target.

[0191] For MEA measurements under pure water conditions, SF-Cu GDE and platinum / titanium GDE were used directly as the cathode and anode electrodes, respectively.

[0192] (D) Electrocatalytic CO2 / carbon monoxide reduction

[0193] Electrochemical tests in the flow electrolyzer and MEA electrolyzer were performed using an electrochemical workstation (CHI660E) connected to a current booster (CHI 680C) except for the MEA electrolyzer stack. CO2 flow was controlled using a mass flow controller (MFC, AlicateScientific MC). Unless otherwise specified, the electrolyte flow rate was 5 mL / min, controlled by a peristaltic pump. Unless otherwise specified, the cathode area in both the MEA and flow electrolyzer was 1 cm × 1 cm. Unless otherwise specified, all ECO2R measurements were performed at room temperature. For all flow electrolyzer measurements, Hg / Hg2Cl2 (SCE, saturated potassium chloride) was used as the reference electrode, and all cathode potentials (relative to Hg / Hg2Cl2) were converted to the RHE scale using the following equation:

[0194]

[0195] Where R is obtained by electrochemical impedance spectroscopy (EIS) at an open-circuit potential of 10. 5 The resistance between the cathode and the reference electrode is measured in the frequency range of Hz to 0.01Hz. For all MEA measurements, the total cell voltage is given directly without iR compensation.

[0196] Under alkaline conditions: For measurements in a flow electrolyzer, 1M potassium hydroxide was used as the electrolyte, and an anion exchange membrane (AEM, Fumasep FAA-3-PK-75) was used to separate the cathode electrolyte chamber and the anolyte chamber. CO2 / carbon monoxide was supplied to the cathode at a flow rate of 30 sccm. For ECO2R in an alkaline MEA electrolyzer, 1M potassium hydroxide was used as the anolyte, and the cathode GDE and anolyte GDE were separated by an AEM (Sustainion X37-50).

[0197] For measurements of the scaled-up MEA electrolyzer stack, an integrated circuit based on an Arduino development board (UNO R3, A000066) was used as an auxiliary monitoring system connected to the CoolTerm serial port terminal application tool. All electrocatalytic CO2 reduction measurements in the scaled-up MEA electrolyzer stack were performed using a custom-designed variable DC power supply (1000 watts). The anolyte and CO2 flow rates were 15 mL / min and 30 sccm, respectively. The reaction temperature was 60 °C.

[0198] (E) Product Analysis

[0199] For electrocatalytic CO2 and carbon monoxide reduction, gaseous and liquid products were quantified using gas chromatography (GC, GC-2030, Shimadzu) and nuclear magnetic resonance (NMR, ECZ500R, 500MHz, JEOL) spectrometry. The GC was equipped with two thermal conductivity detectors (TCDs) for hydrogen, oxygen, nitrogen, helium, carbon monoxide, and CO2 signals, and a flame ionization detector (FID) for methane, ethylene, and ethane signals. The GC consisted of packed columns including two Porapak-N, Molecular Sieve-13X, Molecular Sieve-5A, Porapak-Q, and HP-PLOT AL / S columns, using helium (99.999%) and nitrogen (99.999%) as carrier gases. The CO2 flow rate (f) at the electrolyzer outlet was calibrated. CO2 Helium, used as an internal standard, was supplied at a flow rate of 10 sccm and mixed with the outlet gas stream of the electrolytic cell before being injected into GC(20). The FE of the gaseous products was calculated using the following formula:

[0200]

[0201] Where, N x It is the number of electrons transferred for a specific product (x), F is the Faraday constant, and m x f is the mole fraction of a specific product (x) determined by GC. CO2 It is the molar flow rate of CO2, j 总 It is the total current density.

[0202] Using 500MHz 1 1H NMR spectrometry (ECZ500R, JEOL) was used to analyze the liquid products with water suppression. TSP and D2O were used as reference standards and locking solvents, respectively. The FE of the liquid products was calculated using the following formula:

[0203]

[0204] Where, N x It is the number of electrons transferred for a specific liquid product (x), F is the Faraday constant, and C is the electron transfer rate. x Through 1 The concentration of a specific liquid product (x) determined by H NMR, V x Q is the volume of the electrolyte. 总 It is the total charge.

[0205] Energy efficiency (EE) of semi-electrolyzers and full-electrolyzers 半电解池 and EE 全电解池 ) Calculate according to the following formula (taking the oxygen evolution reaction (OER) as an example of an anodic reaction, and assuming it occurs at an overpotential of 0 volts, (relative to RHE):

[0206]

[0207]

[0208] in, and These are the thermodynamic potentials (relative to RHE) of OER and electrocatalytic CO2 reduction to product (x), respectively. x It is the FE, E of product (x) C The potential applied at the cathode, E 全电解池 It is the electrolytic cell voltage of the MEA system.

[0209] CO2 conversion rate is calculated using the following formula:

[0210]

[0211]

[0212] Among them, f x t is the molar rate of product (x) formation, t is the electrolysis reaction time, and A is the geometric area of ​​the electrode.

[0213] (F) In-situ electrochemical Raman measurement

[0214] In-situ Raman measurements were performed using a custom spectroelectrochemical flow cell with a sapphire window (0.15 ± 0.02 mm thick) fabricated in front of the cathode GDE. Nickel felt was used as the counter electrode. The entire system operated in a dual-electrode setup. Electrolyte (0.1 M potassium hydroxide) was pumped at a constant flow rate of 5 mL / min into the sapphire window above the cathode GDE using a peristaltic pump, resulting in an electrolyte surface thickness of 1.5 mm on the cathode surface. CO2 was supplied to the back of the cathode GDE via a meandering flow channel, guiding a flow rate of 30 sccm controlled by an MFC (Alicat Scientific MC). Raman spectra were collected using a WITEC confocal Raman microscope with an objective (50x) and a 633 nm laser, with 10 accumulation times over a 4-second accumulation period. The recording cell voltage was applied in potentiostatic mode without iR compensation.

[0215] (G) In-situ electrochemical XRD measurements

[0216] In-situ XRD measurements were performed using a custom-designed spectroelectrochemical flow cell in a two-electrode setup. A nickel felt was used as the counter electrode, 0.1 M potassium hydroxide was used as the electrolyte, and CO2 (30 sccm) was supplied to the back of the cathode GDE. Cu Kα radiation was employed. In-situ XRD patterns were collected using an X-ray diffractometer (Rigaku SmartLab 9kW – Advanced) at 45 kV and 200 mA. The single test duration was approximately 8 minutes, ranging from 30° to 85° (2θ). The electrolytic cell voltage was applied and recorded in potentiostatic mode without iR compensation.

[0217] (H) In-situ heated TEM measurement

[0218] In-situ heated TEM measurements were performed at 200 kV on the JEOL Model JEM-2100F using Fusion Select fixtures (Protochips) and porous carbon-coated MEMS E-chips.

[0219] (I) Measurement of lead underpotential deposition

[0220] The relative abundance of copper exposure was determined using lead underpotential deposition (Pb-UPD). Pb-UPD measurements were performed in a three-electrode single-chamber electrolytic cell. Graphite carbon rods and silver / silver chloride (3 M potassium chloride) were used as the counter and reference electrodes, respectively. An L-shaped glassy carbon electrode with a 3 mm diameter sample was used as the working electrode. Nitric acid was added to 0.1 M potassium nitrate containing 1 mMPb(NO3)2, purified by nitrogen, to adjust the pH to 1, which was then used as the electrolyte. Measurements were performed using cyclic voltammetry (CV) at a scan rate of 100 mV / sec.

[0221] (J) Temperature-Programmed Desorption Measurement

[0222] Temperature-programmed desorption (TPD) measurements of CO2 were performed on the samples using an adsorption / desorption system. In a typical experiment, 1 cm² of GDE with a catalyst loading of approximately 1 mg / cm² was ground into powder and placed in a U-shaped quartz microreactor. The outlet of the U-shaped quartz microreactor was then connected to a gas chromatograph (GC-2014, Shimadzu) equipped with a TCD detector. CO2 (40 sccm) was then injected into the U-shaped quartz microreactor and kept flowing for 60 minutes, followed by rinsing the sample with a helium flow (40 sccm) until a stable GC baseline was obtained. TPD measurements were then performed while the temperature was increased from room temperature to 800 / 500 °C at a rate of 10 °C / min, and the GC detected the CO2 desorbed from the sample surface.

[0223] (K)DFT calculation

[0224] All DFT calculations were performed using the Vienna Ab initio Simulation Program (VASP). The generalized gradient approximation (GGA) and the Perdew Burke-Ernzerhof (PBE) exchange-correlation functional were employed to describe the electron exchange and correlation interactions at a cutoff energy of 500 electron volts. To achieve self-consistent calculations, the energy convergence criterion was set to 10. -5 The electron volts were calculated, and the lattice parameters were optimized until the convergence tolerance of the force on each atom was less than 0.05 electron volts. Brillouin zone integration was performed using a 4×4×1 Monkhorst-Pack k-point grid.

[0225] For ideal copper, the copper crystal structure is optimized to have... The lattice constant is determined. For Cu-SF, the unit cell is expanded with a factor of 1.1 and then fully relaxed until convergence. The lattice constant is determined to be... A six-layer p(4×4) supercell with a Cu(111) plane is used, with the bottom three layers fixed. For all planar models, the vacuum thickness along the plane perpendicular to the catalyst is at least [value missing]. To avoid attraction from adjacent periodic mirror images. At all intermediate states, two water molecules are added near the plate surface to account for the effects of solvation.

[0226] The Gibbs free energy (ΔG) of the reaction intermediate is defined by the following formula:

[0227] ΔG=△E+△ZPE-T△S

[0228] Where ΔE is the total energy difference, ΔZPE is the zero-point energy difference, and TΔS is the entropy difference. It should be noted that E(H) is half the energy of H2(g) at 1.013 bar at 298.15 K, and E(H2O) is the energy of H2O(g) at 0.035 bar at 298.15 K, and E(OH) = E(H2O) – E(H). The vibrational frequency at 298.15 K was calculated using density functional perturbation theory, and the zero-point energy and entropy were corrected accordingly.

[0229] (L) Material Characterization

[0230] TEM images were acquired on a JEM-2100F at 200 kV. Aberration-corrected HAADF-STEM images were acquired on a TFS Spectra 300 at 300 kV. GPA analysis of the atomic resolution images was performed using Digital Micrograph software to obtain lattice strain. Strain was measured only perpendicular to stacking faults and twin boundaries, with the lattice far from these defects used as a reference (zero strain). SEM images were acquired on a Tescan MAIA3 field emission instrument. Cu Kα radiation was used on a Rigaku SmartLab 9kW advanced diffractometer. XRD patterns were recorded. XPS spectra were collected using Al Kα radiation on the Thermo Scientific Nexsa X-ray photoelectron spectrometer, with C1s (284.6 eV) as a reference. Hard X-ray absorption spectroscopy measurements were performed at beamline BL01C at the Synchrotron Radiation Research Center (SRRC) in Hsinchu City, Taiwan.

[0231] While the present invention has been described with reference to certain embodiments, other embodiments that will be apparent to those skilled in the art are also within the scope of the invention. Therefore, the scope of the invention should be defined only by the appended claims.

[0232] Industrial application

[0233] This invention provides a stackable MEA electrolyzer system capable of operating on pure water, thereby eliminating carbonate formation and permeation. The system is easy to manufacture and readily scalable to industrial applications and CO2 electrolysis power requirements. This invention is not only cost-effective but also a more environmentally friendly way to reduce CO2. Furthermore, the useful byproducts of the ECO2R reaction generated by this invention are produced in higher quantities.

Claims

1. A membrane electrode assembly (MEA) electrolysis system with pure water feedstock, wherein the MEA electrolysis system is used for the electrocatalytic reduction of CO2 to CO, CH4, C2H4 and C under continuous flow conditions in industrial applications. 2+ Compound, C 2+ The compounds include ethanol, propanol, and acetic acid. The membrane electrode assembly electrolysis system has a lifespan of at least 1000 hours. The membrane electrode assembly electrolysis system includes one or more membrane electrode assemblies, each comprising: anode; cathode; Anion exchange membrane; Proton exchange membrane; A copper catalyst with a stepped surface at the cathode; and Electrolyte in: The cathode is arranged to contact the anion exchange membrane; The anode is arranged to contact the proton exchange membrane; The anion exchange membrane and the proton exchange membrane are arranged to be in contact with each other; The electrolyte is selected from pure water, which is used as a proton source in the positive bias mode of the system for electrocatalytic CO2 reduction at the cathode. The anion exchange membrane is selected from basic anion exchange membranes; The proton exchange membrane is selected from acidic proton exchange membranes; The stepped copper catalyst has a variable surface atomic coordination number from 4 to 9 at one or both of the Cu (111) and Cu (100) exposed surfaces; and Copper catalysts that provide a rich step surface include: Cuprous chloride and octadecylamine were dissolved in squalane at 80°C in an argon atmosphere for 0.5 hours until a copper-based stock solution was formed. Oleylamine and trioctylphosphine were mixed in an argon atmosphere, and the mixture was heated to 200°C while being vigorously stirred to form a mixture; The copper-based stock solution was injected into the mixture at 200°C and maintained for 5 hours to form a reaction mixture; Allow the reaction mixture to cool naturally, centrifuge the cooled reaction mixture, and then wash several times with n-hexane; and After washing, the supernatant was removed, and the particles were dried with argon at room temperature to obtain a solid copper catalyst rich in step surfaces.

2. The system according to claim 1, characterized in that, The cathode is selected from a gas diffusion electrode having at least one layer of copper catalyst rich in step surfaces deposited on it.

3. The system according to claim 1, characterized in that, The anode is selected from one or more of platinum, iridium, ruthenium, and palladium, as well as their oxides or alloys, and is supported on a titanium fiber felt.

4. The system according to claim 1, characterized in that, The electrocatalytic CO2 reduction is carried out at a temperature of 60°C or lower but above room temperature.

5. The system according to claim 1, characterized in that, The alkaline anion exchange membrane is an anion exchange membrane made of N-methylimidazolium-functionalized styrene polymer.

6. The system according to claim 5, characterized in that, The anion exchange membrane has a thickness of 0.002 inches.

7. The system according to claim 1, characterized in that, The acidic proton exchange membrane is a proton exchange membrane made of tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer.

8. The system according to claim 7, characterized in that, The proton exchange membrane has a thickness of 0.007 inches and an equivalent weight of 1100 g / mol.

9. The system according to claim 1, characterized in that, The copper catalyst rich in stepped surfaces has a variable surface tensile strain within 10% of its initial tensile strain, as measured at room temperature.

10. The system according to claim 1, characterized in that, The electrolyte in the cathode is the same as the electrolyte in the anode.

11. The system according to claim 1, characterized in that, At least six of the membrane electrode assemblies are stacked together.

12. The system according to claim 11, characterized in that, When a total current of 10 amps is supplied across the at least six membrane electrode assemblies via two conductive substrates sandwiching the stack, a Faraday efficiency of up to 50% for the conversion to C2H4 is achieved with a CO2 to C2H4 conversion efficiency of 39%, and the stack of the at least six membrane electrode assemblies has a total geometric area of ​​30 square centimeters.

13. A method for manufacturing a membrane electrode assembly electrolysis system with pure water feed, said membrane electrode assembly electrolysis system being used for the electrocatalytic reduction of CO2 to CO, CH4, C2H4 and C 2+ Compound, the C 2+ The compounds include ethanol, propanol, and acetic acid; the membrane electrode assembly electrolysis system has a lifespan of at least 1000 hours; and the method includes: Provides copper catalysts with rich step surfaces; An ink composition containing a copper catalyst rich in step surfaces is prepared for forming a cathode having a copper catalyst rich in step surfaces thereon; A cathode with a stepped surface formed thereon is formed; Preparation of an anode-forming mixture for forming the anode; The anode is prepared from the anode forming mixture of the supporting anode material; An alkaline anion exchange membrane and an acidic proton exchange membrane are disposed between the cathode and the anode. The alkaline anion exchange membrane is arranged to contact the cathode, and the acidic proton exchange membrane is arranged to contact the anode. The alkaline anion exchange membrane and the acidic proton exchange membrane are in contact with each other, thereby forming a multilayer structure of a membrane electrode assembly. One or more membrane electrode assemblies are sandwiched between two conductive substrates; Pure water is supplied as an electrolyte to a container containing one or more membrane electrode assemblies sandwiched between the two conductive substrates. Power is supplied to the one or more membrane electrode assemblies through the two conductive substrates; as well as The electrolyte is maintained at a temperature sufficient to sustain the electrocatalytic reduction of CO2 to C2H4 for at least 1000 hours without the dominant hydrogen evolution reaction. The copper catalyst rich in step surfaces has a variable surface atomic coordination number from 4 to 9 at one or both of the Cu (111) and Cu (100) exposed surfaces; and The copper catalyst providing a stepped surface includes: Cuprous chloride and octadecylamine were dissolved in squalane at 80°C in an argon atmosphere for 0.5 hours until a copper-based stock solution was formed. Oleylamine and trioctylphosphine were mixed in an argon atmosphere, and the mixture was heated to 200°C while being vigorously stirred to form a mixture; The copper-based stock solution was injected into the mixture at 200°C and maintained for 5 hours to form a reaction mixture; Allow the reaction mixture to cool naturally, centrifuge the cooled reaction mixture, and then wash several times with n-hexane; and After washing, the supernatant was removed, and the particles were dried with argon at room temperature to obtain a solid copper catalyst rich in step surfaces.

14. The method according to claim 13, characterized in that, The cathode having a stepped surface formed thereon comprises: A solid copper catalyst rich in step surfaces is dispersed in a mixed solution containing water, isopropanol and an alkaline ionomer solution. Solid copper catalyst with a rich step surface was mixed with a mixed solution for one hour by ultrasonic treatment until an ink composition containing a copper catalyst with a rich step surface was formed. An ink composition containing a copper catalyst rich in step surfaces is coated onto carbon paper with a microporous carbon gas diffusion layer. The ink composition containing a copper catalyst rich in step surfaces, coated on carbon paper, was dried in a vacuum for one hour.

15. The method according to claim 13, characterized in that, The anode is formed from a titanium fiber felt supported by an anode-forming mixture comprising one or more of platinum, iridium, ruthenium, and palladium, as well as their oxides or alloys.

16. The method according to claim 13, characterized in that, The alkaline anion exchange membrane is selected from anion exchange membranes made of N-methylimidazolium-functionalized styrene polymers and having a thickness of 0.002 inches.

17. The method according to claim 13, characterized in that, The acidic proton exchange membrane is selected from a proton exchange membrane made of tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer, having a thickness of 0.007 inches and an equivalent weight of 1100 g / mol.

18. The method according to claim 13, characterized in that, At least six of the membrane electrode assemblies are stacked on top of each other and sandwiched between two conductive substrates; the temperature of the electrolyte is maintained at 60°C.

Images